This invention relates to the field of binary coded cam selector switches and particularly to switches having extremely long life expectancy and reliability.
Many types of rotary switches are known in the art. Many of these employ a plurality of cams and a plurality of switch contracts for providing a given program or sequence of switching functions. As stated in the prior art, the vast bulk of the breakdowns or malfunctions of such rotary switches are due to a malfunction of one or more contacts. Such malfunctions are chiefly due to foreign matter in the contact area. When such malfunctions occur, one of two approaches is usually taken by repair personnel. The first approach is to replace the entire switch. In any application, this is a time consuming repair job. The second approach involves replacement and/or repair of a bad set of contacts. While this approach generally requires less stocking of repair parts, it generally requires much more repair time and the comment has been made that many rotary switches, when taken apart sufficiently to permit replacement of individual contacts, resemble nothing so much as a three dimensional jigsaw puzzle. As stated elsewhere in the prior art, miniaturization decreases operating life and reliability. While efforts have been made to improve the performance of individual contacts and to extend their life, it has not been recognized that with the appropriate approach, the necessity for repair could be postponed beyond any normally expected lifetime of the equipment in which the switch is used.